Hot-blast stove



- Patented May 13, 1947 UNITED STATES PATENT V OFFICE HOT-BLAST s'rovnCarl G. Hogberg, Glenshaw, Pa., assignor to United States SteelCorporation of Delaware, a corporation of Delaware Application September15, 1944, Serial No. 554,242

The present invention relates to improvements in hot blast stoves suchas those used to preheat the combustion air supplied to a conventionalform of blast furnace. I

A primary object of the invention is to provide a hot blast stovehaving. a combustion chamber and a checker chamber with an uprightdivision wall between them including a stratum of heatinsulatingmaterial eflfective to retard the transfer of heat through the divisionwall so as to substantially equalize the temperature throughout theentire cross-sectional area. of the checker chamber at any desiredhorizontal'plane or. zone of the stove.

A further object of the invention is to provide such a division wallhaving incorporated therein a layer of material of lower heatconductivity than that of the remainder of the wall.

A more detailed object of the invention is. to provide a division'wallbetween the combustion chamber and the checker chamber of a hot blaststove with a heat-insulating material of graduated heat conductivityincorporated therein,

which is effective to variably retard the transfer of heat through thedivision wall at different elevations or zones, so as to substantiallyequalize the temperature in the checker chamber at such various zones ofthe stove.

For a more complete disclosure of the invention, reference should bemade to the following detailed description, the accompanying drawings,and the appended claims.

In the drawings:

Figure 1 is a vertical longitudinal section through a hot blast stoveembodying the invention.

5 Claims. ((1263-19) 2 supplied during the heating cycle. During suchcycle the air and gas are intermingled and burned in the combustionchamber 20, and the Products of combustion flow through the numerouspassageways formedby the checkerbrick flyth'us" giving up their heatthereto. The products of combustion then pass to a suitable stack (notshown) by way of an exhaust port 30. .When the stove is on blast, coldair enters through port 32,

passes upwardly through the multiplicity of flues' and 2, there isincorporated in the division wall an interior layer of material Itcharacterized by a lower rate of heat conductivity than the portions lBand l8 of the wall. The portions l8 and 18 may be formed of theconventional type of refractory brick normally used in hot blast stoveconstruction and the material forming the stratum IE will be of acharacter to retard the transfer of heat through the division wall forthe express purpose of substantially equalizing Figure 2 is a horizontalsection on line II--Il of Figure 1.

Figure 3 is a fragmentary detail of a portion of the division wallbetween the combustion and checker chambers of the stove, including astratum of heat-insulating material of varying heat conductivity atdifferent horizontal zones of the stove.

Referring in detail to the drawings, reference numeral l0 represents theouter annular refractory brick wall of the stove which is usuallyenclosed by a substantially cylindrical steel shell l2. At the top thereis in substantially semispherical brick roof l4 covered by a dome-shapedthe temperature in the checker chamber throughout substantially theentire cross-sectional area thereof at any desired horizontal zone orregion of the stove. As illustrated in Figure 3, the thickness.

of the stratum of heat-insulating material It may vary at differentelevations of the furnace, so as to provide a predetermined heatconductivity gradient. Instead of varying the thickness of the stratum I8, it may be of uniform thickness throughout but of differing densitiesor compositions at different elevations to provide any desired gradientof heat conductivity. The thickness of the heat-insulating material maybe gradually increased from bottom to' top, or vice versa, and may beentirely omitted at a predetermined point in the height of the wall, tosuit the design or requirements of any given size of stove.

The herein claimed invention overcomes a troublesome problem which isinherent in hot blast stoves of conventional form. In such conventionalstoves, during both the checker heating and air heating periods, theaverage temperature in the lower portion of the combustion chamber isconsiderably higher than the average temperature in the lower region ofthe checker chamber. This temperature differential may vary fromapproximately 600 F. to 1400" F.

during the air heating cycle, and from approximately 1500 F. to 2250 F.during the checker heating period. Due to the higher average temperaturein the lower portion of the combustion chamber, during both the checkerheating and air heating periods, the refractory checkerwork immediatelyadjacent to an uninsulated division wall will be higher in temperaturethan the checkerwork more remote from the division wall. This differencein temperature in prior'art construction is of sufllcient magnitude toinduce a differential expansion and contraction of the checkerwork in agiven horizontal plane of the checker chamber, with resultant damage ordestruction of the checkerwork or supports therefor in the base of thestove. The claimed invention overcomes this shortcoming inherent inprior art constructions by substantially equalizing the temperature ofthe checkerwork throughout the cludlng an outer annular brick wall, anupright entire cross-sectional area at any given horizontal plane orregion of the stove.

While I have illustrated the invention as embodied in a type of hotblast stove having a combustion chamber of approximately ellipticalform, it will be understood that the invention is also applicable to hotblast stoves in which the combustion chamber is formed by an innersubstantially circular wall either concentric to or tangent to the outerwall, it being obvious that the principles of the invention will applyby incorporating a body of heat-insulating material in any wallseparating the combustion chamber from the checker chamber.

I claim:

1. A hot blast stove for heating blas: furnace combustion air,comprising an upright, substantially hollow structure having an uprightdivision wall dividing the interior of the stove into a combustionchamber and a checker chamber, said division wall including outer strataof fire-brick separated by a dissimilar stratum of heat-insulatinmaterial effective to retard the transfer of heat through saidfire-brick strata.

2. A hot blast stove for heating blast furnace combustion air,comprising an upright, substantially hollow structure-having an uprightdivision wall dividing the interior of the stove into a combustionchamber and a checker chamber, said division wall including outer strataof firebrick separated by dissimilar stratum of heatinsulating materialof graduated heat conductivity effective to retard the transfer of heatthrough said fire-brick strata so as to substantially equalize thetemperature throughout the entire area of the checker chamber at anydesired horizontal zone thereof.

division wall, a body of checker brick between one face of said divisionwall and said annular wall, and a combustion chamber bounded by theother face of said division wall and said annular wall, said divisionwall consisting of two layers of conventional refractory brick spacedapart by a layer of material of lower heat conductivity than that of therefractory brick, the composite wall being effective to retard thetransfer of heat therethrough so as to substantially equalize thetemperature in the checker chamber at any desired horizontal zonethereof.

4. A hot blast stove for heating blast furnace combustion air,comprising a hollow structure having an outer annular brick wall, anupright division wall, a-body-of checker brick between one face of saiddivision wall and said annular wall,

and a. combustion chamber bounded by the other face of said divisionwall and said annular wall, said division wall consisting of two layersof refractory brick spaced apart by an interior brick layer of materialof lower heat conductivity than that of the brick layers, the compositedivision wall being eflective to retard the transfer of heattherethrough so as to substantially equalize the temperature in thechecker chamber at any desired horizontal zone thereof.

5. A hot blast stove for heating blast furnace combustion air,comprising a substantially hollow structure including an outer annularbrick wall, an upright division wall, a, body of checker brick betweenone face of said division wall and said annular wall, and a combustionchamber bounded by the other face of said division wall and said annularwall, said division wall consisting of two layers of refractory brickspaced apart by a layer of insulation of graduated heat conductivity tosubstantiall equalize the temperature in the checker chamber at varioushorizontal zones of the stove.

CARL G. HOGBERG.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,849,657 Boynton Mar. 15, 19322,049,815 McGee Aug. 4, 1936 2,257,453 Bowland Sept. 30, 1941

